Читать книгу Animal Behavior for Shelter Veterinarians and Staff - Группа авторов - Страница 95

After some experience learning a target behavior with one person, a dog might respond to a discriminative stimulus (such as “sit”) from other people. Responding to the same cue from a different person is an instance of generalization. Conversely, if the dog does not respond to a cue by that different person, then the dog is said to discriminate between cues (the cue given by the trainer versus the cue given by the new person). To put it simply, stimulus generalization occurs when an animal responds similarly to different stimuli, whereas stimulus discrimination occurs when an animal responds differently to different stimuli. The extent to which an organism generalizes or discriminates between stimuli is indicative of varying degrees of stimulus control (Cooper et al. 2007).

Animals can learn to discriminate or generalize very subtle features of a stimulus. Nagasawa et al. (2011) demonstrated this aspect of discrimination and generalization with dogs. In their study, dogs were presented two pictures: one of their owner’s smiling face and one of their owner’s neutral face. Touching the smiling picture resulted in a reinforcer, whereas touching the neutral face did not. The dogs learned to choose the smiling picture of their owner most often, meaning that they learned to discriminate between the two pictures. When presented with a smiling and neutral picture of an unfamiliar person, dogs responded similarly in that they chose the smiling face most of the time. The dogs generalized to pictures of novel individuals. Interestingly, though, the dogs were only successful in generalizing their responses to pictures of novel individuals of the same sex as their owner. Since they only learned the discrimination task with one sex, they discriminated between sexes.

The processes of discrimination and generalization are complex; generalization more readily occurs when two stimuli are similar, whereas discrimination readily occurs when two stimuli are very different. In Nagasawa et al.’s (2011) study, the pictures of the smiling face and neutral face were very different, which helped the dogs learn to discriminate between them. The pictures of their owner and another person of the same sex were similar enough that the dogs were able to generalize across those stimuli and choose the smiling face. However, the pictures of their owner and another person of a different sex were distinct enough that generalization did not occur.